The improved design of safety shell structures around the driving compartment of a motor vehicle, and the improvements in the shock absorbing characteristics of engine compartments, have meant that it is now much less likely that the driver of a vehicle in a front-end collision will be killed outright. With that increase in vehicle safety comes another concern, which is that the driver whose life has been spared by good vehicle design should not become injured or trapped in the vehicle by the pedal box structure around the driver's feet.
Brake and clutch pedal boxes have been proposed which collapse on application of an excessive load such as that applied by the forward momentum of a driver when the vehicle is in a front-end collision. A collapse of the pedal box in such a situation permits the pedals of the vehicle to move forward and away from the driver's feet, providing important extra legroom to reduce the risk of the driver's feet becoming trapped in the accident. Even a few centimeters of extra legroom in such circumstances can be a significant safety advantage.
Various prior proposals for collapsible pedal box design have contemplated making the pedal box collapse dependent on the impact itself. It is however important to reduce as much as possible the extent to which the reaction pressure of the driver's foot on the pedal or pedals is necessary to initiate pedal box collapse. Similarly it is important to reduce as much as possible the reliance on any other member which might come into contact with the driver, such as a steering column member, as a source of the reaction pressure.
A collapsible pedal box has previously been described in EP 0827874. The pivot shaft is journalled between pivot shaft supports which are permanently mounted on the inner surface of the opposing side walls. In the event of a frontal impact, a member in the passenger compartment collides with the front of the two side walls forcing them apart while on the engine side the side plates are brought together. Accordingly, the two pivot shaft supports are forced apart to release the pivot shaft. However, since the two side walls twist in opposite directions during the impact, the two pivot shafts are unable to move mutually apart along the axis of the pivot shaft and so there is a greater likelihood that the pivot shaft will still be retained by one of the supports after impact.
Another collapsible pedal box has been described in our WO-A-02/30718. A pivot shaft for the pedal or pedals is journalled at its ends in discrete pivot shaft supports which are physically locked with respect to side walls of the pedal box until there is a front-end impact of the vehicles. Then the pivot shaft supports are unlocked so that they can move mutually apart along the axis of the pivot shaft, to release the pivot shaft and initiate collapse of the one or more pedals.
Both of the above prior proposals require that end supports for the pivot shaft move apart in mutually opposite directions. In the case of a particularly violent front end collision the pivot shaft itself may be bent, which could resist the movement apart of the two end supports. It is therefore an object of the invention to create a collapsible pedal box in which the pedal box collapse is initiated without requiring axial movement apart of opposite end supports of the pivot shaft in mutually opposite directions.